vv ISSN: 2640-7930 DOI: https://dx.doi.org/10.17352/gjz LIFE SCIENCES GROUP Received: 09 October, 2019 Research Article Accepted: 09 January, 2020 Published: 10 January, 2020 *Corresponding author: Md. Simul Bhuyan, Faculty A baseline taxonomic study of Marine Sciences and Fisheries, University of Chittagong, Chittagong, Bangladesh, Tel: +88- 01849752555; E-mail: of zooplankton in the lower Keywords: Taxonomy; Composition; Zooplankton; Indian major carps; Lower Halda River Halda River, Bangladesh https://www.peertechz.com Istiak Ahamed Mojumder1, Md. Manzoorul Kibria1 and Md. Simul Bhuyan2* 1Halda River Research laboratory, Department of Zoology, University of Chittagong, Chittagong, Bangladesh 2Faculty of Marine Sciences and Fisheries, University of Chittagong, Chittagong, Bangladesh Abstract Halda is a unique resourceful tidal river of Bangladesh, where Indian major carps (Catla catla, Labeo rohita, Cirhinnus mrigala, and Labeo calbasu) spawn from April to June. Ecological conditions are auspicious from time immemorial which serves as a natural breeding ground in the world. The present study was conducted over the period of January-June 2017 to identify the main species of Zooplankton fauna and also fi nd out the dominancy of the highest plankton groups in the lower Halda River. A total of 3 major zooplankton groups-Copepoda, Rotifera and Cladocera were identifi ed during the six months period. A total of 35 species under 4 family showing the dominancy for the class Rotifera consisting of 7 genera were recorded from fi ve sampling sites. The lowest group was Cladocera consisting of 5 genera. The composition and dominance of the zooplankton community among fi ve different sites in the lower Halda River showed some close inter-relationships. The present study suggests for conducting further research to know the overall conditions and to make a complete list of available zooplankton fauna that exert impact on the water quality of the Halda River. Introduction minute aquatic animals that are non-motile or very weak swimmers. They serve as a good indicator of changes in water Bangladesh is blessed with small and large rivers which quality because it is strongly affected by the environment are mostly covered with water. The Halda River is one of the quality [6]. They play a crucial role in indicating the presence most unique resourceful rivers of Bangladesh where Indian or absence of certain fi shes. Zooplankton population is able to major carps (Catla catla, Labeo rohita, Cirrhinus mrigala, and refl ect the nature and potential of any aquatic systems [7,8]. Labeo calbasu) spawn during April to June [1-3]. The river also provides navigations, supplies drinking water and generate Zooplankton constitutes an important food item of many employment opportunities for the local communities [1]. omnivorous and carnivorous fi shes. The larvae of white fi sh (Mullet) feed mostly on zooplankton [9], because zooplankton The biotic community of an ecosystem gives an insight into provides the necessary amount of protein for the rapid growth the conditions existing in the aquatic ecosystem. Changes in and especially that of the gonad. Zooplankton contributes the structure and function of biological systems are induced about 82% of the food item of Anabas testudineus [10], 32% of by environmental disturbances in the composition of aquatic Notopterus notopterus [11]. The main food item of Xenentodon communities of rivers [4]. Zooplankton is one of the four cancila and the zooplankton contributes about 23% of the food selected bioindicators (benthic diatom, zooplankton, littoral item of Macrobrachium rosenbergii, 47% of the Catla catla and macroinvertebrate, and benthic macroinvertebrate), uses 6.37% of the Labeo rohita [12]. for assessment in Ecological Health Monitoring (EHM) [5]. Zooplankton is considered the most important link between Resources of the Halda River are depleting day by day planktonic primary producers and large carnivores, amongst due to over-fi shing, straightening of existing ox-bow bands, them fi sh species subject to human exploitation. They are sedimentation on the river bed, changes in water quality, 001 Citation: Mojumder IA, Kibria MM, Bhuyan MS (2020) A baseline taxonomic study of zooplankton in the lower Halda River, Bangladesh. Glob J Zool 5(1): 001-008. DOI: https://dx.doi.org/10.17352/gjz.000013 https://www.peertechz.com/journals/global-journal-of-zoology mismanaged sluice gate establishment, mechanical sand quarrying, water contamination with industrial wastes, denudation of various species of fi shes towards gradual extinction including carps, unchecked riverbank erosion and above all global climate change [1]. Time may come when no more seed will be available from the Halda if the Halda River ecosystem destroyed. Therefore, the protection of the Halda River is an urgent need because most of the country’s pond carp culture reliant on the fi sh fry naturally produced in this river which is of insurmountable economic and nutritional value. The taxonomic checklist of zooplankton along with its occurrence and distribution in the lower Halda River has become a prerequisite for fi sh production. Available information about the Halda River reveals that only a few works have so far been done in the country by different researchers. Thus, there is a research gap that needs to be bridged. Considering these facts, the present study was aimed to determine the main species of zooplankton fauna in the lower Halda River, Chittagong by making its list in terms of zooplankton species composition and group’s dominance. The present study will be a preliminary baseline for the zooplankton study in the lower Halda River. Materials and methods Study Area The present study was carried out in the tidal Halda River (22°54′ N and 91°48′ E to 22°24′ N and 91° 53′ E), one of the tributaries of the River Karnaphuli originated from Haldachora at the area of 2 no (Table 1, Figure 1). Patachora Figure 1: Map showing the sampling sites of the study area. Union in Ramgarh Upazila under Khagrachari districts (former Chittagong Hill Tracts), Bangladesh [13]. A number of canals bring the pollutants in the Halda River. The study of plankton such as Manikchori Khal, Khondokia Khal, Madari Khal, Khata of these sites gives an insight into the effects of environmental Khal are connected with the Halda River and make Halda Khal variables on the biodiversity and ecosystem of the Halda River a river [13,14]. and how the overall productivity fl uctuates from site to site as Geological information well as gives the decision-makers a basis for coming up with its better management. Five important sites named Karnaphuli (estuary), Krisno Khal, Khandokia Khal, Madari Khal and Garduara (Noyahat) Sampling duration were selected purposively for sample collection. There are The sampling was carried out from January to June 2018. a number of canals in the fi sh sanctuary of the Halda River. Water samples containing zooplankton were collected from Khandokia Khal is one of the most polluted canals where selected fi ve points over the period of six months at the time untreated wastewater from the adjacent industries and Anannya of 6:30-10:00am but some time due to unfavorable condition residential area fl ow through the canal and fi nally ends up in time had to change. Samples were collected every month form the Halda River. Kalurghat is the confl uence point of Halda and Karnaphuli River. Saline water from the Bay of Bengal enters every site. the Halda River through the Karnaphuli River. During ebb and Sample collection and preservation fl ow, the water of the Karnaphuli River mixes with the water of the Halda River through this confl uence point. These indirectly Zooplankton samples were collected from the subsurface water using a zooplankton net of 70μm mesh size. A fl ow meter Table 1: Geographical positions of the sampling sites. was attached at the mouth of the net. The net was thrown to GPS locations the desired distance (7m) and allowed to reach the desired Stations No. Name of the sites Latitude Longitude depth of the sampling sites from the boat. Then the throne Site 1(S1) Karnaphuli (estuary) N 22°23′59″ E 91° 53′17″ rope with the net was pulled quickly towards the boat for the Site 2(S2) Krisno Khal N 22°30′10″ E 91° 52′7″ collection of samples. The water was passed down through the Site 3(S ) Khondokia Khal N 22°43′05″ E 91° 87′54″ 3 net and the plankton condensed at the end of the plankton net Site 4(S ) Madari Khal N 22°26′58″ E 91° 51′32″ 4 then it was collected into a glass test tube and fi xed fi rmly. The Site 5(S5) Garduara (Noyahat) N 22°50′01″ E 91° 86′59″ 002 Citation: Mojumder IA, Kibria MM, Bhuyan MS (2020) A baseline taxonomic study of zooplankton in the lower Halda River, Bangladesh. Glob J Zool 5(1): 001-008. DOI: https://dx.doi.org/10.17352/gjz.000013 https://www.peertechz.com/journals/global-journal-of-zoology net was pulled 3 times from several places of the sites. Then Results and discussion the samples were transferred to a plastic jar, labeled detective of time, date and sampling sites. The collected samples were Zooplankton species composition preserved in 5% formalin in the plastic jars immediately after A total of 35 species of zooplankton was identifi ed. 15 collection and were taken to the laboratory of the Department species of Rotifera belonging to 4 family and 7 genera; 9 species of Zoology, University of Chittagong. For further study, samples of Copepoda belonging to 2 family and 5 genera; 9 species of were preserved in 70% alcohol. Cladocera belonging to 4 family and 5 genera also pelecypod Identifi cation larva, Nauplius larva, etc. were recorded from the lower Halda River during the study period.